FIG. 1 shows an exemplary network structure of an Evolved Universal Mobile Telecommunications System (E-UMTS) as a mobile communication system to which a related art and the present invention are applied. The E-UMTS system is a system that has evolved from the UMTS system, and its standardization work is currently being performed by the 3GPP standards organization. The E-UMTS system can also be referred to as a LTE (Long-Term Evolution) system.
The E-UMTS network can roughly be divided into an E-UTRAN and a Core Network (CN). The E-UTRAN generally comprises a terminal (i.e., User Equipment (UE)), a base station (i.e., eNode B), a serving gateway (S-GW) that is located at an end of the E-UMTS network and connects with one or more external networks, and a Mobility Management Entity (MME) that performs mobility management functions for a mobile terminal. One eNode B may have one or more cells.
FIG. 2 shows an exemplary architecture of a radio interface protocol between a terminal and a base station according to the 3GPP radio access network standard. The radio interface protocol is horizontally comprised of a physical layer, a data link layer, and a network layer, and vertically comprised of a user plane for transmitting user data and a control plane for transferring control signaling. The protocol layer may be divided into L1 (Layer 1), L2 (Layer 2), and L3 (Layer 3) based upon the lower three layers of the Open System Interconnection (OSI) standards model that is widely known in the field of communication systems.
Hereinafter, particular layers of the radio protocol control plane of FIG. 2 and of the radio protocol user plane of FIG. 3 will be described below.
The physical layer (Layer 1) uses a physical channel to provide an information transfer service to a higher layer. The physical layer is connected with a medium access control (MAC) layer located thereabove via a transport channel, and data is transferred between the physical layer and the MAC layer via the transport channel. Also, between respectively different physical layers, namely, between the respective physical layers of the transmitting side (transmitter) and the receiving side (receiver), data is transferred via a physical channel.
The Medium Access Control (MAC) layer of Layer 2 provides services to a radio link control (RLC) layer (which is a higher layer) via a logical channel. The RLC layer of Layer 2 supports the transmission of data with reliability. It should be noted that if the RLC functions are implemented in and performed by the MAC layer, the RLC layer itself may not need to exist. The PDCP layer of Layer 2 performs a header compression function that reduces unnecessary control information such that data being transmitted by employing Internet Protocol (IP) packets, such as IPv4 or IPv6, can be efficiently sent over a radio interface that has a relatively small bandwidth.
The Radio Resource Control (RRC) layer located at the lowermost portion of Layer 3 is only defined in the control plane, and handles the control of logical channels, transport channels, and physical channels with respect to the configuration, re-configuration and release of radio bearers (RB). Here, the RB refers to a service that is provided by Layer 2 for data transfer between the mobile terminal and the UTRAN.
Hereinafter, description of a method for receiving data by a terminal in the LTE system will be given. As shown in FIG. 4, the base station and the terminal generally transmit/receive data through a Physical Downlink Shared Channel (PDSCH) using a transport channel DL-SCH, with the exception of a specific control signal or a specific service data. Also, information on which terminal (or a plurality of terminals) should receive data of the PDSCH or information on how the terminals should receive the PDSCH data and perform decoding, is transmitted by being included in the physical layer PDCCH (Physical Downlink Control Channel).
For instance, it is assumed that a certain PDCCH is under a CRC masking as an “A” RNTI (Radio Network Temporary Identifier), and is being transmitted in a certain sub-frame by including information about data being transmitted in transfer format information “C” (e.g., a transport block size, modulation and coding information, etc.) through radio resources “B” (e.g., a frequency location). Under such condition, one or more terminals in a corresponding cell may monitor the PDCCH by using their own RNTI information. If there are one or two or more terminals having A RNTI at a corresponding point of time, the terminals shall receive the PDCCH, and also a PDSCH indicated by B and C through the received information on PDCCH.
During this procedure, an RNTI is transmitted to inform that allocation information of radio resources transmitted through each PDCCH conforms to which terminals. The RNTI is divided into a dedicated RNTI and a common RNTI. The dedicated RNTI is used for data transmission/reception to a certain terminal. The common RNTI is used when data is transmitted or received to/from terminals to which the dedicated RNTI is not allocated since its information is not registered in the base station or when information commonly used by a plurality of terminals (e.g., system information) is transmitted. For instance, during the RACH procedure, RA-RNTI or T-C-RNTI is the common RNTI.
In the related art, an RRC connection should be established to perform a call establishment between the terminal and the base station. During the RRC connection process, a security setup is required. However, the process for the security setup is not performed by a test method through a security setup-related message having more reliability, thereby causing a problem of inefficiently performing an authentication between entities in a radio (wireless) call connection process.